The answer to 'hydro jetting overflowing' is that hydro jetting can sometimes cause a clogged drain to temporarily back up or overflow. This is usually due to the high-pressure water dislodging debris that then gets stuck in the pipe, causing a temporary blockage.
To prevent this, make sure the drain is clear of any obstructions before starting the hydro jetting process. If the drain does overflow during jetting, stop the process immediately and try plunging or using a drain snake to clear the blockage. If the overflow persists, it's best to call a professional plumber to properly diagnose and resolve the issue.